In packaging granulated or pulverized food products and products having sifting characteristics, it has been customary in the food industry to employ cartons provided with pouch liners formed from moisture impervious papers, foils or plastics. Such pouch liners typically have ends which are fused by heat to form closure ridges or fins. Once opened, the carton is resealed by folding or rolling the open ends of the inner pouch.
In order to effect cost savings in material and production machinery, and extended product shelf life, the packaging industry has developed and marketed linerless cartons provided with thermoplastic moisture-proof coatings and barrier closures. This approach is exemplified by U.S. Pat. Nos. 2,795,364 and 2,886,231, both to B. Benzon-Petersen, which are directed to cartons having rectangular parallelepiped configurations and a closure formed by hingedly attached and overlapping closure flaps. A barrier seal is obtained by attaching a sealing membrane to the flaps when they are oriented in an outward direction prior to their closure. However, this structure does not provide a moisture barrier once the membrane seal is broken limiting the usefulness of the package.
An alternative carton arrangement is disclosed in U.S. Pat. No. 3,190,531 to Holmstrom, which shows a membrane sealing sheet attached to interior surfaces of carton closure flaps. In order to provide a resealing feature, the membrane is attached to one flap at areas which outline an inwardly oriented U-shaped arch, and a sidewall panel adjoining the flap is provided with crease lines which form a spout. The spout is provided by severing the sealed bottom end of the U-shaped arch to define an opening to the interior of the carton, see FIGS. 1-3. The container is resealed by folding the flap across the opening in the container and interlocking the closure flaps.
Another approach of the prior art, represented by U.S. Pat. No 2,719,663 to G. Meyer-Jagenberg, shows a carton cover structure including an aperture flap having an incised cut area and an overlying covering flap which is attached to the aperture flap by an adhesive coating. Outward pivoting of the covering flap effects severance of the incised area to define a pour spout. The cover is reclosed by pressing the covering flap into adhesive contact with areas surrounding the pour spout. The closure is recessed within the carton and secured in position by overlying peripheral flanges in the covering and aperture flaps which form a U-shaped surface for attachment to an upper end of the carton body. See FIG. 7.
Difficulty with the recessed cover structure in Jagenberg is presented by the arrangement of attachment flanges which require complicated folding operations during assemblage. Further difficulties are associated with the adhesive bond between the aperture and covering flaps which limit the effectiveness of release and reseal features in the cover.
The present invention is directed to an improved linerless carton having a recessed sealing membrane and resealing structure of uncomplex design and enhanced effectiveness over prior art pouch and adhesive closures. The invention advances known moisture barrier closures by incorporating a reclosable pour spout structure which functions without requirement of an adhesive bond. It will be appreciated that linerless cartons provide cost savings in materials and manufacturing efficiencies over pouch arrangements, and that a reclosable moisture barrier carton with an effective dispensing spout will meet a need of the packaging art.
Accordingly, it is the broad object of the present invention to provide an improved moisture barrier carton of economical design which is easily opened and resealed by the consumer.
A more specific object of the invention is to provide a linerless carton incorporating a closure membrane which obtains a moisture barrier seal improved over the prior art.
A still further object of the invention is to provide a moisture barrier closure which includes a pour spout for dispensing foodstuff.